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Activity Based Models Review. presented to Model Task Force Model Advancement Committee presented by Thomas Rossi Krishnan Viswanathan Cambridge Systematics Inc. Date November 24, 2008. Presentation Overview. Study Background and Objectives Models Studied Study Findings Discussion. - PowerPoint PPT Presentation
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presented to
Model Task Force Model Advancement Committee
presented byThomas RossiKrishnan ViswanathanCambridge Systematics Inc.
Date
November 24, 2008
Activity Based Models Review
2
Presentation Overview
Study Background and Objectives
Models Studied
Study Findings
Discussion
3
Study Background and Objectives
Examine existing activity based models to determine model features, application procedures, and requirements
Determine planning analysis needs for which travel models are used
Summarize the ability of activity based models to provide accurate information for planning analysis needs
4
Models Studied
Urban Models• San Francisco County, CA (2001)• New York, NY (2002)• Columbus, OH (2005)• Sacramento, CA (2007)• Lake Tahoe, NV/CA (2007)• Atlanta, GA• Portland, OR• Denver, CO• San Francisco Urban Area (MTC), CA
5
Models Studied (Cont’d)
Statewide Models• Ohio Model (2007)• Oregon Model
Research Models• FAMOS (University of South Florida)• CEMDAP (University of Texas)• TASHA (University of Toronto)
6
Models Studied (Cont’d)
SFCTANew York
Columbus
Sacramento
Lake Taho
e AtlantaPortlan
d Denver
San Francisco (MTC) Ohio
Oregon
Year Completed 2001 2002 2005 2007 2007 2008 (est.)
2008 (est.)
2008 (est.)
2009 (est.)
2007 2008 (est.)
Base Year 2000 1996 2000 2005 2000 2000 2005 2000Forecast Year 2020 2030 2035 2030 2035 2030,
2050Survey Data Year 1990 1998 1999 2000 2001 1994 1997 2000 2003 No
Survey
Number of Households in Survey
1,300 11,000
5,600 3,900 1,220
8,100 6,000 4,900 15,000 15,000
No Surve
yZones (approximate)
1,700(750 in
SF)
3,600 1,800 1,500 289 2,000 2,000 2,800 1,454 5,300 3,000
Area Size (square meters)
50 (SF
only)
150 (est.)
4,000 501 500 7,000
Base Year Population
750,000
(SF only)
1,500,000
2,000,000 63,448
4,700,000
1,600,000
6,783,760
7
Study FindingsModel Structure
All models estimated from household activity/travel survey• Same type of survey used for four-step model
development
Individuals in region’s population are simulated• Activity patterns• Locations and times of activities• Modes used to travel between activity locations
8
Study FindingsModel Structure (Cont’d)
Model structure• Generate daily activity patterns• Location, time and mode made at two levels : Tour and Trip
Five to eight activity purposes• Work, school, shop, meal, social/recreation, and personal
business
Some models consider household interactions• Implications for time of day and mode choice• Is it cost effective to include this to gain accuracy? The “jury is
still out.”
9
Study FindingsModel Components
Population Synthesizer
Long Term Choice Models
• Auto ownership
• Usual workplace location
Daily Activity Pattern Models
Tour Level Models (primary activity)
• Destination choice
• Mode choice
• Time of day choice
10
Study FindingsModel Components (Cont’d)
Trip Level Models (intermediate stops)• Destination choice• Mode choice• Time of day choice
Trip Assignment• Highway• Transit
11
Study Findings Model Development Process
Model development between 1.5 to 8 years (typically 2-3 years)
Model development costs – typically $600,000-$800,000
Consultants nearly always used for model development
Most models used local household activity survey data along with other sources such as transit on-board, external or visitor surveys
Lake Tahoe model was transferred from Columbus
12
Study Findings Model Execution
Standard transportation modeling software such as CUBE/Voyager, TransCAD used along with custom programs in C++, Java, or Python
Run times range from 10 hours to 2 days • Distributed computing preferable to reduce runtime
Models need around 7 to 10 GB of storage per run
Most models run only in-house
13
Study Findings Policy Planning Analysis
Activity Based Models benefit the following types of analysis• Congestion Management Systems • Toll Feasibility Studies • High-Occupancy Vehicle (HOV) Lane Studies • New Starts/Small Starts Analyses • Hurricane Evacuation Modeling Support • Air Quality Conformity Determinations • Integrated Land Use Model • Incorporate Ability to Test Impact of Gasoline Prices • Freight Studies• Growth Management/Concurrency Applications
14
Study Findings Data Needs
No special data needs required to develop activity based models beyond what is used for four-step models
Existing household travel surveys can be used to develop data for activity based models
Other data sources such as transit on-board surveys, external and visitor surveys are also helpful for activity based models
Census data sources such as PUMS useful for population synthesis
• ACS disclosure rules can be problematic
15
ConclusionsModels use similar approaches• Main differences related to explicit modeling of household
interactions
Members of population simulated individually• Their activities, locations, times, and mode choices
Standard modeling software used along with custom programs
Typically 2-3 years, $600,000-$800,000 to develop models
Run times typically 0.5 to 2 days
16
Discussion
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